The structure of the lipoprotein from the outer membrane of E. coli will be determined by a combination of electron microscopy, electron and optical diffraction. The lipoprotein forms paracrystals with large areas of regular lattice and negatively stained electron micrographs will be scanned, Fourier transformed, filtered and back transformed to give the tertiary arrangement of the lipoprotein in the paracrystals. Low dose defocused electron micrographs of unstained lipoprotein and their diffraction patterns taken both normally and with tilted specimens will be used to provide the structure amplitudes and phases, necessary for calculating the three dimensional electron density of the lipoprotein molecule. Crystals of the complex of the bound form of the E. coli lipoprotein and hen egg white lysozyme will be grown and the structure of the complex will be determined by conventional x-ray diffraction techniques.